A year ago, Rebecca Knight and her pal Karen England were singing for spare change in the piazza of London’s famed Covent Garden.

Both have classically trained voices, but it wasn’t their superior singing that got them through a day of busking in damp London town – it was three pairs of socks.

“You have to keep your feet warm,” Knight told The Post.

Thanks to those warm feet, their ability to hit a high C – and their blond good looks – the two were spotted by a talent scout.

Reborn as the OperaBabes, they’ve lived a Cinderella story since making “Beyond Imagination,” filled with duets from “Madame Butterfly,” “Carmen” and more, with contemporary arrangements. The album has topped the English charts for three months and will be released here on Tuesday.

The idea is pretty simple: The emphasis is on pretty. England, a soprano, and Knight, a mezzo-soprano, are counting on the babe factor.

“People who have never listened to opera before might get drawn in by two pretty girls,” Knight said.

After that, she says, it’s their talent that turns listeners into fans. “The best thing we can hear is when people tell us after a show, ‘I never thought I’d like opera, but you changed my mind.’ That’s what it’s all about.”

England, 28, and Knight, 32, could pass for sisters. Both are married to violinists, Jonathan and Noely, respectively, and live outside London. Neither has children, but Knight keeps rabbits and sports a couple of tattoos. A compass is etched on her body – for her love of sailing – and the Sanskrit symbol for the mantra om.

England sees no tattoos in her future, not even one that says OperaBabes. “What if we broke up?” she asked. “That would be hard to change into a dagger or something, wouldn’t it?”

Post: Your album is fun, but opera purists will accuse you of compromising classics for mass appeal.

Knight: That’s very hard to respond to. There’s a snobby hierarchy in opera, and it’s a shame. Karen and I often go to the opera house and we turn up wearing jeans, looking what would be considered normal anywhere else. At the opera, we’re looked down on by some people. I think they are the kind who would dislike our interpretations.

Post: So what do you say to the snobs?

Knight: That we haven’t destroyed the last existing copy of the original. If they’re that upset that we put English lyrics to the “Ode to Joy,” they really don’t have buy it or even listen.

England: We’re not out there to offend people; we’re there to make them happy. And a lot of people who have heard the album are happy with it.

Knight: The other thing is, we don’t take that sort of criticism seriously.

Post: But you are serious musicians.

England: We both come from very solid classical backgrounds. We’ve worked hard to get proper roles in serious opera. What OperaBabes is, is a fantastic avenue that allows people to appreciate this kind of music, but we will always be involved in traditional opera.

Post: There’s a story that you two became friends over Chinese medicine.

England: God, I wish I’d never said that. It wasn’t quite like that. We were in a touring company together doing “The Magic Flute,” and a man came and lectured us all on how certain Chinese medicines affect the voice. Suffice to say, he didn’t keep to the topic very well, and Rebecca and I got rather silly and we ended up on the floor crying with laughter.

Knight: We’re not that sort. Even if we were, we’d never go up for the same part because our voices are so different.

England: Rebecca and I have very different voice types, personalities and ways of doing things – that’s why our friendship is so strong. It’s why we work well together.

Post: How are you alike?

England: We have great confidence in our abilities.

Knight: We’re also happy to be on stage. It’s not that we don’t enjoy the opportunity to do solo stuff, but when we’re on stage, I never feel competition.

Post: Are your stage costumes sexy?

England: They are not as gratuitous as they are glamorous. We’re not Christina Aguilera.

Post: There are those who think opera singers should be full-bodied.

Knight: You mean fat. The world thinks that. It’s really just a stereotype. Not all opera singers are large.

Post: So it isn’t true that you need the girth to belt out the notes?

England: The people who are very large already believe that they need to have their weight. They’re afraid if they lose weight, they will lose their voice.

Knight: See, when you sing, you can’t be afraid of taking deep, deep breaths, and that makes you look bigger. We all have the tendency to try and hold our stomachs in – that just doesn’t work for a singer.

Post: If OperaBabes succeeds in America, do you think you’ll still be welcome in traditional opera circles?

Knight: Certainly. We haven’t turned our backs on it. We do a whole mixture of music. We can have commercial success and still stand on a classical stage, because we can deliver the goods – we’re the genuine articles.

England: Some of the music might cross over to pop, but our voices don’t.

Knight: Exactly. We don’t need a backing track. We can stand there and sing with a full symphony orchestra unaided by amplification. Christina Aguilera has many things going for her, but I doubt she could do that.

Post: Describe what you do with the music.

Knight: We sing properly. Everything is spot on. The twist we put into opera is not in our singing, but in the backing arrangement.

Post: People who don’t know opera often have the perception it’s dull. How do you bring excitement to the music?

Knight: We have rapport with each other, we both know stagecraft and we know how to interact with any audience.

Post: You mean any opera audience?

England: No, any audience. We used to busk.

Knight: We’d sing in the street at Covent Garden. When you do that, you meet people from every walk of life, so we know we can entertain anyone.